Cutting tool assemblies for such applications as continuous mining, excavating, or road milling typically comprise a cutting tool, sometimes called a cutting bit, rotatably mounted within a support block. The support block in turn is mounted onto a drum or other body, typically by welding, which in turn is driven by a suitable drive mechanism. When a number of such support blocks carrying cutting tools are mounted onto a drum, and the drum is driven, the cutting tools will engage and break up the material which is sought to be mined or removed. The general operation of such a mining, excavating, or road milling machine is well known in the art.
Because the support block is exposed, it is subject to wear and abuse and must be cut or torched off the drum and replaced when unusable. In order to prolong the life of the support block, a cutting tool sleeve, sometimes referred to as a bit sleeve, tool holder, or bit holder, is sometimes employed. The cutting tool is mounted within the tool sleeve which in turn is mounted within the support block. The tool sleeve generally has an outer wear surface which helps to protect the support block from abuse and wear during use, thus minimizing the down time otherwise required for support block replacement and drum repair. The use of such tool sleeves is well known in the art.
For example, U.S. Pat. No. 5,067,775, to D'Angelo et al., hereby incorporated by reference in its entirety, discloses the use of a tool sleeve. More specifically, and as illustrated in FIGS. 1, 2 and 3 of the D'Angelo et al. patent, the tool sleeve has a larger diameter forward portion and a smaller diameter rearward portion joined by an inclined region. When inserted into the bore of a support block, the smaller diameter rearward portion of the sleeve extends out of the back of the block and has a groove in which a retainer member is mounted. The inclined region of the tool sleeve fits against an inclined region of the tool block such that the sleeve is held in the block with a slight degree of axial movement freedom. The sleeve is also relatively freely rotatable in the support block. The sleeve, of course, includes a tool bore into which a cutting tool may be rotatably or otherwise mounted. Because the larger diameter forward portion of the sleeve protrudes from the cutting block, it bears the brunt of any abusive wear to which the support block would otherwise be subjected.
Many typical tool sleeve retention systems, such as the one disclosed in the D'Angelo et al. patent, allow the tool sleeve to rotate within the support block. In typical mining or road milling applications, especially those involving abrasive materials, dust, dirt or other debris may get into the support block bore, or otherwise between the tool sleeve and support block, and cause excessive wear to both the tool sleeve and the support block.
Various methods have been proposed or used in the past to limit or prevent rotation of a tool sleeve within a support block.
An example is shown in FIG. 1 which is an isometric view of a prior art steel clip 10 having a wavy configuration with inner apexes 12 and outer apexes 14 which was made by Kennametal Inc., located in Bedford, Pa. As shown in FIG. 2, this steel clip 10 was used with a tool sleeve 16 having a clip groove 18. More specifically, the steel clip 10 was used by placing it within the clip groove 18 as shown in FIG. 2 before inserting the tool sleeve 16 within a support block bore. The clip groove 18 was located along the longitudinal length of the tool sleeve 16 such that it would be located within the support block bore when the tool sleeve 16 was fully inserted. As a result, the steel clip 10 would be compressed within the support block bore and the inner apexes 12 and outer apexes 14 would frictionally engage both the clip groove 16 of the tool sleeve 18 and the support block bore to reduce rotation of the tool sleeve 18 relative to the support block. However, such prior steel clips 10 would sometimes fail during use as the result of wear or fatigue, especially of the inner apexes 12 or outer apexes 14, making the clips 10 unable to fulfill the function of minimizing rotation of the tool sleeve 16 within the support block bore.